A fuel cell system, which generates electric current from an anode gas and a cathode gas in the usual manner, may reach comparatively high temperatures during operation, especially if the fuel cell used in it is an SOFC fuel cell. To switch off the fuel cell system, it is usually necessary to carry out a predetermined switch-off procedure or switch-off routine in order to switch off the fuel cell system in such a way that this is as gentle for its components as possible. Furthermore, it must be ensured that no critical gas mixture concentrations will build up and that no unacceptably high pollutant emissions will take place. In particular, an attempt is made by a specific switch-off procedure to avoid soot formation within the fuel cell system. This leads to reduced pollutant emissions, reduced fuel consumption, longer service life for the fuel cell system and increased efficiency for the fuel cell system. Furthermore, operating a fuel cell is not permitted in certain environments of the vehicle, for example, in closed spaces, for example, garages and closed parking garages or at a gas station.
In addition, it may also be necessary for switching on such a fuel cell system to perform a predetermined switch-on procedure or switch-on routine in order to switch on the fuel cell system or to run up the power of the fuel cell system in such a way that it is as gentle for its components as possible. For example, it must also be ensured when running up the power that no critical gas mixture concentrations will build up and no unacceptably high pollutant emissions will take place.